手撕一下二分查找

直接放源码。

​​​​​​​package defaultPk;

public class BiterySearchDemo {
    public static void main(String[] args){
        int[] a=new int[]{1,2,3,4,5,6,7};
        int result=binarySearch(a,0,6,3);
        System.out.println(result);
    }
    public static int binarySearch(int arr[],int low,int high,int key){
        int mid=(low+high)/2;
        if(arr[mid]==key){
            return mid;
        }
        if(high>=mid){
            if(arr[mid]<key){
                return binarySearch(arr,mid+1,high,key);
            }
            else{
                return binarySearch(arr,low,mid-1,key);
            }
        }
        else{
            return -1;
        }
    }
}